1. Field of the Invention
This invention relates to an air inlet grille having airflow director blades (louvers) and more particularly to novel indexing means for controlling the position of those louvers.
2. Description of the Prior Art
Air distribution devices have long been available, which are characterized by adjustable louvers. These differ among themselves as to (i) the means for directionally adjusting the louvers and/or (ii) the manner for temporarily retaining one or more of the louvers in a selected directional orientation.
Louver directional adjustment is typically accomplished by rotating the louver on an axis parallel to the long dimension of the louver. Louvers typically have one pivot point at each end and are retained at this pivot point in the grille frame. Typical methods for providing the pivot point for a louver include a portion of the louver extending through a hole in the frame, or a screw or other fastener means driven through a hole in the frame and into the louver.
Louvers may be adjusted individually, or by acting on two or more louvers at once ("gang operated" louvers). Individually adjustable louvers have the potential advantage of more precise air flow control, since each louver can be adjusted to its optimal position. On the other hand, gang operated louvers can be more convenient to adjust, as the one adjustment controls several or all of the louvers in a grille. Often, gang operated louvers are worked by a linkage which can be accessed more conveniently than could the louvers individually.
Known air distribution devices typically retain the louvers in a selected position by means of frictional engagement and/or an indexing device.
The most common method for retaining louvers is with friction. Relatively smooth surfaces are in contact and resist sliding, owing to the coefficient of friction and clamping forces between the two parts. Examples of this kind include the use of wire against a round louver end pivot (U.S. Pat. No. 2,991,707 Goettl); a flat spring-loaded surface pressing against a parallel flat planar surface of a louver (U.S. Pat. No. 3,180,246 Johnson); a spring-loaded screw end pressing against a cylinder attached to the end of a louver (U.S. Pat. No. 2,236,865 Bailey et al); or a spring-loaded expandable round pivot point on the grille fitted into a hole on the frame (U.S. Pat. No. 3,270,657 Jaye). Since grilles are typically manufactured from materials that are hard and smooth (e.g. metal or plastic) they inherently have a low coefficient of friction. Louvers retained in a set direction only by the resistance of sliding friction between two components may not be capable of withstanding forces that unintentionally cause the louver to rotate into an undesired orientation.
The second method for retaining louvers in a given position employs an indexing device. The sliding surfaces between the rotating louver and a fixed point on the grille (for example, the frame) are provided with geometric features which are intended to increase the resistance to adjustment of the louver direction from certain selected positions.
One typical method of louver indexing uses a wire spring pressing against a square or rectangular section of the louver end. The square or rectangular section of the louver end is approximately at the pivot point around which the louver rotates. As it does so, the louver will naturally rest in a position where the spring rests flat against one side of the square or rectangular section of the louver as exemplified in U.S. Pat. No. 2,759,410 (Hurt, Jr.). In this arrangement, however, if a louver is adjusted away from its resting point it may unexpectedly adjust back to the resting point when vibrated, thus limiting the range of reliable settings for the louver.
A second indexing method employs a leg integral to the louver, acting as spring as the louver is rotated across undulations in the frame as illustrated, for example, in U.S. Pat. Nos. 5,338,252 (Bowler et al.) and 5,626,517 (Kil). Such an arrangement requires the louver material to be capable of acting resiliently, so limiting the choice of materials from which the louvers may be fabricated.
It is a principal object of the present invention to provide a new louver indexing device for grilles which exhibits a high degree of reliability and reproducibility of the indexing function.
It is a further object of the invention to provide indexing means giving distinct tactile feedback to a person adjusting a louver to any of a selected number of discrete angular positions.
It is a further object of the invention to provide indexing means which resists accidental louver repositioning by reason of vibration, airflow force or other loads.
It is a still further object of the invention to provide louver indexing means which may be used with louvers fabricated from a wide range of structural materials.